The primary goals of our first set of studies is to determine the effectiveness, and localize the neuronal sites of action, of four naturally occurring androgens in the stimulation of sexual and agonistic behavior in castrate male Swiss-Webster mice. Testosterone, dihydrotestosterone and 3 alpha - and 3 Beta -androstanediol have been selected for these studies since they have been shown to be either accumulated or metabolically produced within the brain and other androgen target tissues. In our initial experiments we will systemically administer these androgens, first to gonadally intact males and hemi-ovariectomized female to assess their potency in feedback suppression of gonadotropin secretion, and second to castrated males to assess their potency in the induction of sexual and agonistic behavior. These experiments will run parallel to an intracerebral implantation experiment, in which we plan to map the neuronal loci in which testosterone propionate cannulas can activate sexual and/or agonistic behavior in castrate male mice. Following this experiment we plan a second intracerebral implantation experiment, this time using the naturally occurring androgens found to be effective in the systemic administration experiments. These experiments are designed to test the hypothesis that different hormone metabolites may be maximally effective in different regions of the brain and/or in the activation of different behaviors. In a second set of studies we plan to investigate the inhibitory actions of progesterone and the anti-androgen cyproterone acetate in androgen induced sexual and agonistic behavior in castrate male mice. In these experiments we plan to use both systemic and intracerebral implantation techniques to establish the potency and neuronal loci for the inhibitory actions of these steroids.